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Gas String Trimmer Stops Running

#1

B

billy3p

Make- Homelite
Model- Bandit SX 135
i was given this unit when a young teenager's parents bought him a replacement for his summer lawn care business. I assume it was due to intermittent operating issues but I got two growing seasons of use from it with little issues. Now, I am unable to get it to continue to run after less than 10 minutes of starting and using it. It is my understanding this model was made with two different walbro carburetors? If so, how can I determine which kit I would need to search for and order if I want to consider rebuilding the carburetor? Or, any input as to what else might be the issue is appreciated.


#2

sgkent

sgkent

Remove the gas cap, put it back on and see if it starts. If so then the tank vent system is not properly venting. On some it is a small breather hose that can swell shut. Also clean the air filter. Every small motor like that I have had die after running because of a bad carb diaphragm does so after a few seconds, not ten minutes.


#3

7394

7394

And if that doesn't help, dump a capfull of Seafoam in the gas tank, shake well & try again.


#4

StarTech

StarTech

billy3p said:
Make- Homelite
Model- Bandit SX 135
i was given this unit when a young teenager's parents bought him a replacement for his summer lawn care business. I assume it was due to intermittent operating issues but I got two growing seasons of use from it with little issues. Now, I am unable to get it to continue to run after less than 10 minutes of starting and using it. It is my understanding this model was made with two different walbro carburetors? If so, how can I determine which kit I would need to search for and order if I want to consider rebuilding the carburetor? Or, any input as to what else might be the issue is appreciated.
Click to expand...
Remove the carburetor and looking the Walbro model numbers. From there post them and someone should be able to look up the carburetor and give the correct kit numbers.

But is likely a WT-458-1 (WT-458A) which uses the D20-WAT gasket and diagram kit or the K20-WAT carburetor repair kit.


#5

B

billy3p

I used this string trimmer on 04/11/22. After about 15 minutes of run time it starting losing power like it was choking out. I adjusted the butterfly position and was able to get it to operate at full speed for about another 5 minutes before it started losing power again. Is it possible the issue is that the butterfly valve or choke control position lever is closing the butterfly valve due to vibration?


#6

B

billy3p

So today while using this string trimmer I could see the choke lever handle move from a position where the unit was operating as it should to a position where the engine started losing power and choking due to what I assume is the butterfly valve inside the carb closing. Any suggestions on how to fix this issue are appreciated and thank you.


#7

StarTech

StarTech

7394 said:
Most 2 strokes have a plastic flap that covers the tiny carb opening connected to choke lever, behind the air filter. This is how it chokes. You gotta think of something like a piece of painters tape to put on & keep choke lever in open position, after running. ..

No butterflies in these carbs. Suggest: You remove the air filter cover (1 screw) & take out filter & see the choke flap & arm, & you will better understand,. Do not re-tighten cover up too tight.
Click to expand...
Then how does it control the engine speed?

And btw the way according to the following it does have both a throttle vane (butterfly) and a Choke vane (butterfly).
1650628297525.png
And carburetor is still available from Walbro.
1650628987694.png
and choke shaft itself is available.
1650629167507.png
If you remove the choke shaft there is usually a steel ball and spring that detent the choke shaft.


#8

7394

7394

StarTech said:
Then how does it control the engine speed?
Click to expand...
My Bad I was referring to my vintage Honda Tiller, that has a barrel in carb opening to accelerate..


#9

B

billy3p

Uploading a few pictures of the carb. The choke shaft looks to be made out of brass maybe? Anyone here seen one like it and removed the shaft?

Attachments









#10

StarTech

StarTech

An older Walbro carburetor. I had a few of them. Still uses a spring and ball to lock it in place and brass shaft will wear out the dimples.


#11

B

billy3p

So, in your honest opinion, can i possibly repair it and if so how do I determine if I can?
Thank you


#12

sgkent

sgkent

An older Walbro carburetor. I had a few of them. Still uses a spring and ball to lock it in place and brass shaft will wear out the dimples.
Click to expand...
sounds reasonable, if so replace the shaft if available or use a drill bit by hand twirling it to clean up the dimple.


#13

B

billy3p

What is the procedure for removing the shaft if I can ask?
Thanks again.


#14

B

billy3p

I am on the fence about keeping this string trimmer or recycling and replacing it. How can I determine the specific model of the Walbro carburetor this unit has since there were several models used on different string trimmers?


#15

sgkent

sgkent

you may have to research it by comparing what yours looks like to what is for sale. A genuine carb for that general model on Ebay is $75. Some of the clones and alternates are in the $20 range. Is it worth it? An Internet search engine should help you find diagrams of the trimmer and the model carb it used if you have the model and serial.


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